The basic question we want to answer is whether less energy would be expended (and less work involved) if the woman brought her groceries upstairs by making a single trip, carrying all three bags at once, or if she made multiple trips, carrying one bag at a time (or two bags on the first trip and one bag on a second trip). Work is defined as F × d, the force multiplied by distance, or ΔE, the change in energy. The change in energy experienced in this problem is a change in potential energy, so W = ΔE = mgΔh.

First scenario: one trip carrying all three bags at once

m = ...